Today's computer networks are usually comprised of multiple interconnected computer systems. Some of the computer systems are configured for use by individuals/users. These computer systems are normally referred to client or local computer systems. Other computer systems, also present within the network, are configured to facilitate the interaction between the client or local computer systems and the network to which they are connected. These other computer systems are commonly referred to as server or host computer systems. Additionally, it is common for many of today's large companies to have hundreds or thousands of servers and client computer systems exchanging information.
Further, both the server and client computer systems generate vast amounts of data containing a nearly endless variety of information. Portions of the data can contain information that can be deemed mission critical and needs to be archived in some manner.
Currently there are numerous types of data storage systems that are designed to store the vast amounts of data. Examples of various data storage systems can include, but ate not limited to, tape backup, disk mirroring, CD storage, multiple intercoupled storage devices, and others.
A commonality among many types of data storage systems is the requirement of a power source, e.g., AC mains. Another similarity among many types of data storage systems is that data is first placed in a buffer or cache memory before it is written to the storage device or to the array of storage devices.
However, it is unrealistic to presume that AC mains will never cease to function. Brown-outs or black-outs, natural disasters, acts of terrorism, power generator failures, fires, and downed power lines, are but a few of the types of occurrences that can cause AC mains to become temporarily non-functional. Further, when an AC main fails, it is quite common for any information that was placed in cache to be lost. This is especially disadvantageous for important information that had yet to be written to a non-volatile data storage medium
To overcome this disadvantage, many data storage devices are coupled with a UPS (uninterruptible power supply) that provides power when there is an AC main failure. Another method of providing backup power includes placing batteries on the computer system board. Yet another method of providing backup power is to place a battery on the controller, and in this method, when the system is rebooted, there is an image of the data that was placed in the cache, which is then regenerated.
A disadvantage to this is that if there is an extended outage, e.g., from 96 to 120 hours, and by virtue of the backup power having a finite amount of energy stored therein, the energy contained in the backup power device may become exhausted, thus causing a loss or corruption of the information.
An additional disadvantage is that backup batteries can, over time, lose some of their ability to provide a consistent backup charge. It is common for backup batteries not to remain fully charged. Accordingly, if an AC main goes down, there is a possibility that the backup battery may not have enough energy to enable writing of the buffer or cache memory before battery power is exhausted.
High current batteries, e.g., NiCad batteries, have been used mainly in the power tool arena and other low tech, non-mission critical environments. Further, high tech battery applications have been utilized in laptop batteries, which do not require the high current, high temperature demand of large storage systems, e.g., rack mounted systems.